The disclosure relates generally to display technology, and more particularly, to method and apparatus for subpixel rendering.
Displays are commonly characterized by display resolution, which is the number of distinct pixels in each dimension that can be displayed (e.g., 1920×1080). Many displays are, for various reasons, not capable of displaying different color channels at the same site. Therefore, the pixel grid is divided into single-color parts that contribute to the displayed color when viewed at a distance. In some displays, such as liquid crystal display (LCD), organic light emitting diode (OLED) display, electrophoretic ink (E-ink) display, or electroluminescent display (ELD), these single-color parts are separately addressable elements, which are known as subpixels.
Various subpixel arrangements (layouts, schemes) have been proposed to operate with a proprietary set of subpixel rendering algorithms in order to improve the display quality by increasing the apparent resolution of a display and by anti-aliasing text with greater details. For example, LCDs typically divide each pixel into three strip subpixels (e.g., red, green, and blue subpixels) or four quadrate subpixels (e.g., red, green, blue, and white subpixels). For OLED displays, due to the limitation of fabrication process, subpixels cannot be arranged too close to each other.
Color rendering approach has been applied to reduce the number of subpixels in each pixel without lowering the display resolution. PenTile® technology is one of the examples that implement the color rendering approach. In designing subpixel arrangements for displays, it is desired that different colors of subpixels, e.g., red, green, and blue subpixels, are uniformly distributed, i.e., the numbers of each color of subpixels are the same, and the distances between different colors of subpixels are substantially the same. However, for subpixel arrangements using PenTile® technology, the number of green subpixels is twice of the number of red or blue subpixel, i.e., the resolution of red or blue color is half of the resolution of green color. The distance between two adjacent subpixels with different colors (relative distance) also varies for subpixel arrangements using PenTile® technology.
It is also commonly known that each pixel on a display can be associated with various attributes, such as luminance (brightness, a.k.a. luma,) and chrominance (color, a.k.a. chroma) in the YUV color model. Most of the known solutions for subpixel rendering use native display data generated based on the RGB color model, which consists of three primary color components, red (R), green (G), and blue (B). However, since the human vision system is not as sensitive to color as to brightness, the known solutions of using three or four subpixels to constitute a full-color pixel and rendering the subpixels using native RGB display data may cause the waste of display bandwidth and thus, are not always desirable.
Accordingly, there exists a need for improved method and apparatus for subpixel rendering to overcome the above-mentioned problems.